The Spelevo exploit kit (EK) abuses a vulnerability affecting Flash Player to infect users with samples of the Maze ransomware family.
Security researcher nao_sec, who was the first to publicly report the new Maze ransomware campaign, noted that it redirects users to Spelevo, according to Bleeping Computer. The exploit kit attempts to abuse CVE-2018-15982, a use-after-free vulnerability, within the browser to specifically target users of Flash Player versions 188.8.131.52 / 184.108.40.206 and earlier. If it finds a vulnerable user, Spelevo exploits the weakness and leverages arbitrary code execution to install Maze on the user’s computer.
Upon successful infection, the ransomware sample analyzed by Bleeping Computer began scanning the computer for interesting files, including documents and photos. It then used RSA encryption and the ChaCha20 stream cipher to encrypt all the files it could find before dropping a ransom note into every folder containing affected data. The note instructed victims to visit a website hosted on the Tor network for payment instructions.
Tracking the Evolution of Spelevo
Spelevo is a relatively new cyberthreat that is still evolving. Researchers at Malware-Traffic-Analysis.net first spotted the exploit kit in March 2019. At the time, the threat was using Flash-based exploits.
Around the same time, Fox-IT observed Spelevo distributing PsiXBot, a modular piece of malware.
How to Defend Against the Maze Ransomware Campaign
Security professionals can help their organizations defend against Maze ransomware borne by exploit kits such as Spelevo by connecting their comprehensive vulnerability management solutions to their security information and event management (SIEM), networking monitoring and patch management tools to help streamline the response to new security bugs. Additionally, security teams should craft a patch management strategy that espouses thoughtful prioritization and collaboration among different teams.